Marijuana is legal in Massachusetts, but the feds are still looking to prosecute cases here in these three areas

US Attorney Andrew Lelling, the top federal prosecutor in Massachusetts, on Tuesday pointed to three marijuana-related areas his office plans to focus on as the state keeps moving into the era of legal pot.

The Cannabis Control Commission, the new state agency tasked with overseeing the burgeoning industry, has started issue the licenses needed for retail pot shops to open in Massachusetts.

The commission was created through a voter-approved state law legalizing marijuana, but the drug remains illegal at the federal level.

"Because I have a constitutional obligation to enforce the laws passed by Congress, I will not effectively immunize the residents of the Commonwealth from federal marijuana enforcement," he said. "My office's resources, however, are primarily focused on combatting the opioid epidemic that claims thousands of lives in the Commonwealth each year."

He added that the three areas for potential marijuana prosecutions will include "overproduction," "targeted sales to minors," and "organized crime and interstate transportation of drug proceeds."

"Overproduction" of marijuana could lead to illegal sales in nearby states that haven't yet legalized marijuana for recreational use, according to Lelling. "These out-of-state sales are nearly always cash transactions and so often involve federal tax fraud designed to hide the illicit cash or its true source."

Lelling said he expected marijuana use among minors to increase, and the "targeted sale of marijuana to minors may warrant federal prosecution."

The law passed by Massachusetts voters in November 2016 broadly legalized use of recreational marijuana for adults ages 21 and over.